紫色土坡耕地土质埂坎稳定性数值模拟

发布时间：2018-06-09 13:29

本文选题：土质埂坎 + 紫色土　；参考：《重庆师范大学》2017年硕士论文

【摘要】：埂坎通过分割坡长和降低坡面坡度控制坡耕地土壤侵蚀,具有较好的水土保持效果。在三峡库区坡耕地整治、高标准基本农田建设等工程中,土质埂坎因其造价低、施工方便、生态适宜、调控侵蚀效果较好,仍占较大比例,与石质埂坎同等重要,但确保土质埂坎的稳定是保护坡耕地的前提。经野外大量调查后选取了典型紫色土埂坎分层采集土壤样品,利用激光粒度分析仪、应变控制式直剪仪测试埂坎土壤物理、力学参数,运用应力变形分析法模拟不同规格埂坎应力应变分布特征,采用极限平衡分析法计算不同规格埂坎在自然工况和土壤吸水饱和工况条件下的稳定性系数,构建了稳定性系数对埂坎高度和外边坡坡度的响应模型。主要研究结果如下:(1)紫色土坡耕地土质埂坎与坎后土壤基本物理性质没有显著性差异。自然工况下,埂坎上层土壤抗剪强度大于中层和下层。埂坎和坎后土壤吸水饱和后,抗剪强度均降低。(2)紫色土坡耕地埂坎基部至顶部,最大总应力逐渐减小。埂坎高度一定时,随着外边坡坡度增加,腰部和基部最大总应力呈变大趋势,顶部变化趋势不明显。埂坎顶部和腰部X 总应力均随埂坎外边坡坡度的增加而减小,基部则变大。埂坎外边坡坡度一定时,随着埂坎高度增加,最大总应力和X 总应力均呈变大趋势。(3)紫色土埂坎高度一定时,随着外边坡坡度增加,X 位移最大值逐渐从埂坎基部下方掩埋区移动到埂坎基部上方临空面。埂坎外边坡坡度一定时,随着埂坎高度增加,X 位移没有发生特别明显的重分布,位移最大值区域相对较固定。(4)紫色土坡耕地土质埂坎稳定性系数随高度增加或外边坡坡度变陡而降低,但高度与外边坡坡度的交互效应对稳定性的影响不显著。埂坎土壤吸水饱和后,稳定性系数显著降低,其中,“低缓”型土质埂坎稳定性系数降低更明显。(5)紫色土坡耕地土质埂坎的潜在滑动面主要有直线形和圆弧形两种,“高陡”型埂坎潜在滑动面多为直线形,“低缓”型埂坎潜在滑动面多为圆弧形。土壤吸水饱和对潜在滑动面形态没有明显影响。
[Abstract]:The ridge has better soil and water conservation effect by dividing slope length and reducing slope gradient to control soil erosion of sloping land. In the three Gorges reservoir area slope cultivated land regulation, high standard basic farmland construction and other projects, because of its low cost, convenient construction, ecological suitability, good control and erosion effect, it still occupies a large proportion, and is as important as the stone ridge. But to ensure the stability of the ridge is the premise to protect the sloping land. After a large number of field investigations, soil samples were collected from typical purple ridge ridges. The soil physical and mechanical parameters were measured by laser particle size analyzer and strain-controlled direct shear apparatus. The stress and strain analysis method is used to simulate the stress and strain distribution of the ridge with different specifications, and the stability coefficient of the ridge with different specifications under natural conditions and saturated soil water absorption conditions is calculated by using the limit equilibrium analysis method. The response model of stability coefficient to ridge height and slope is constructed. The main results were as follows: (1) there was no significant difference in the basic physical properties of the soil between the ridge and the back of the purple soil. Under natural conditions, the shear strength of the upper layer of the ridge is higher than that of the middle layer and the lower layer. The shear strength of soil decreased after water absorption and saturation of ridge and ridge. 2) the maximum total stress gradually decreased from the base of ridge to the top of ridge in purple soil. When the height of ridge is constant, the maximum total stress of waist and base increases with the increase of slope, but the change trend of top is not obvious. The total stress at the top of the ridge and at the waist decreases with the increase of slope gradient outside the ridge, but the base becomes larger. With the increase of ridge height, the maximum total stress and X ~ (+) total stress of the slope outside the ridge show a trend of increasing when the slope gradient is constant) when the height of the purple ridge is constant, the maximum total stress and the total X _ (+) stress are increased. With the increase of slope of the outer slope, the maximum displacement is gradually moved from the buried area below the ridge base to the empty surface above the ridge base. When the slope gradient outside the ridge is constant, with the increase of the height of the ridge, there is no obvious redistribution of the displacement. The maximum displacement region is relatively fixed. 4) the stability coefficient of slope ridge in purple soil is decreased with the increase of height or steepness of external slope, but the interaction effect between height and slope is not significant. The stability coefficient of "low slow" type ridge is significantly decreased after the soil water absorption saturation. Among them, there are two kinds of potential slip surface of purple soil sloping land ridge: linear shape and circular arc shape, and the decrease of stability coefficient of "low slow" type ridge is more obvious than that of "low slow" type soil ridge. The potential slip surface of "high and steep" ridge is mostly linear, and the potential slip surface of "low and slow" type ridge is mostly circular arc. Soil water absorption saturation has no obvious effect on the morphology of potential sliding surface.
【学位授予单位】：重庆师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S157

【参考文献】